This invention relates to a cylinder piston device of the type used e.g. in vehicle constructions as a counter-weight for a boot flap or an engine bonnet. It is desirable that in such constructions the boot flap or engine bonnet can be positioned in at least one additional position between the fully closed position and the fully open position. This requirement exists both in those cases in which the cylinder piston device provides a lifting force sufficient to overcome the weight of the respective boot flap or engine bonnet and also in these cases in which additional force must be exerted on the flap or bonnet by hand in order to open the flap or bonnet, respectively.